A new class of precursor polymers, as first described by Louwet et al. [1], was used to make organic LEDs. Device properties are relatively independent from the side chain to be eliminated. However introduction of two methyl groups onto the phenyl ring introduces significant changes in absorption, photoluminescence (PL) emission, FL quantum efficiency and electroluminescence spectra. From XRD there is an indication that this effect might be related to a different packing of the polymer chains.